The top plate is the upper horizontal framing member of a stud wall. It is typically the same width as the studs and bottom plate and is some type of stress-graded dimensional lumber, commonly 2x4 or 2x6. Nails are driven perpendicular through the top plate into the studs and cripples to secure them in place on a specific layout, either 16” or 24” on center. Splices can be placed at one or more studs in field applied framing to create a longer wall than otherwise would be possible with stock lengths.
In wall panel applications, multiple panels can be set in succession to create a longer wall that is joined at the double plate (also known as the very top plate) to create as long of a wall as desired. It is common to see automated layout markings for studs, king studs, jack studs, and cripples applied when the top plate is cut to length by an automated computer driven saw derived from the wall panel CAD software. This adds efficiency and accuracy to the wall panel manufacturing process. The top plate serves an important role in providing wood fiber for the perimeter nailing of structural and/or insulated sheathing.
A second top plate, also known as a “double plate” or “very top plate” is applied in the field to lock together intersecting walls. Occasionally, field framed and manufactured wall panels will be built with a large portion of the double plate attached with gaps left at wall intersections to speed up the process when the walls are being installed. Often, construction documents specified by the architect and/or engineer of record will specify double plate parameters such as joint laps and length. A best practice is to consult the construction documents or the local building code for this information prior to installation. It is common practice for framers to ”square” the walls when installing the double plate to ensure the structure is true to dimensions and the walls are plumb. Advanced framers will apply truss spacing layouts on the double plates prior to putting them in place to aid and speed up truss installation. This information can also be applied when the double plate is being cut by computer driven saws in wall panel applications involving information derived from wall panel CAD software.